1. Field of the Invention
The present invention relates to a mobile terminal in a mobile communication system, and more particularly, to a position information transmitting method of a mobile terminal.
2. Description of Background Art
In a mobile communication system, the position information of a user of a mobile terminal is generally determined by using one or more of the following methods: time of arrival (TOA) method; angle of arrival (AOA) method; and time difference of arrival (TDOA) method.
The TOA method requires the use of a plurality of base stations situated around a mobile terminal that measure the time of arrival of a transmission signal from the mobile terminal to calculate a distance between the base stations and the mobile terminal. Using the calculated distances as radii, virtual circles are drawn by the base stations and the point of intersection among the base stations' virtual circles is deemed as the position of the mobile terminal.
The AOA method also requires the use of a plurality of base stations situated around a mobile terminal. The base stations in this method measure the direction in which a transmission signal is received and draw a virtual line in the measured direction. The point of intersection of the base stations' virtual direction lines signifies the position of the mobile terminal.
The TDOA method requires the use of a plurality of base stations situated around a mobile terminal. The base stations in this method draw virtual hyperbolas by using the time difference of arrival between the transmission signal receptions at the base stations. A common intersection of the hyperbolic curves indicates position of the mobile terminal.
With respect to the three aforementioned methods, information regarding the position of a mobile terminal is limited to or contained within the base stations. A mobile terminal user cannot determine- or provide calculated or exact position information to others unless one or more base stations transmit an information signal providing position information. A mobile terminal user must voice or type via short message service (SMS) the description of the terminal's physical location. Therefore, a solution is required for a mobile terminal user to have the terminal's position information available for personal knowledge and/or transmission to others.